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Heterogeneous Reaction of Shattercane to Periconia circinata and its Host-Specific Toxin. L. D. Dunkle, Associate Professor, Department of Plant Pathology, University of Nebraska, Lincoln, 68583, Present address: USDA-SEA, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907; Phytopathology 69:260-262. Accepted for publication 31 August 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-260.

A collection of shattercane (Sorghum bicolor) from southeastern Nebraska contained a portion (35 to 40%) of seeds that was susceptible to the causal agent of milo disease, Periconia circinata, and to its host-specific toxin. The shattercane was not affected by inoculation with an isolate of the fungus nonpathogenic to grain sorghum nor by culture filtrates of the nonpathogenic isolate processed by the same methods used to prepare toxin from the pathogen. The level of susceptibility to the toxin was quantitatively intermediate between that of homozygous susceptible and heterozygous (F1) grain sorghum genotypes. The remaining seeds (60 to 65%) as well as those of two other shattercane collections were resistant. Implications of these findings relative to the single-gene source of resistance to P. circinata are discussed.

Additional keywords: pathotoxin, Periconia root rot, wild cane, Pc gene, sorghum.